What is the GDP price index and what is its role in differentiating nominal GDP and real GDP?

The GDP price index, also known as the GDP deflator, is a measure of the level of prices of all new, domestically produced, final goods and services in an economy. Its primary role is to differentiate nominal GDP, which is measured at current market prices, from real GDP, which is adjusted for inflation to reflect the true value of goods and services. By using the GDP price index, economists can convert nominal GDP into real GDP, allowing for a more accurate comparison of economic output over time, free from the effects of price changes.